Endoscopy allows a physician to view organs and cavities internal to a patient using an insertable instrument. This is a valuable tool for making diagnoses without needing to guess or perform exploratory surgery. The insertable instruments, sometimes referred to as endoscopes or borescopes, have a portion, such as a tube, that is inserted into the patient and positioned to be close to an organ or cavity of interest.
Endoscopes first came into existence in the early 1800's, and were used primarily for illuminating dark portions of the body (since optical imaging was in its infancy). In the late 1950's, the first fiber optic endoscope capable of capturing an image was developed. A bundle of glass fibers was used to coherently transmit image light from the distal end of the endoscope to a camera. However, there were physical limits on the image quality this seminal imaging endoscope was able to capture: namely, the number of fibers limited the resolution of the image, and the fibers were prone to breaking.
Now endoscopes are capable of capturing high-resolution images, as endoscopes use various modern image processing techniques to provide the physician with as natural a view as possible. However, sometimes it may be desirable to see contrast between organs imaged. For instance, some cancers look very similar to surrounding healthy tissue.